Calcining
Sulphur and arsenic are impurities often found in association with tin ore.
The earliest method of disposing of them was by burning until the arsenic was oxidised; the
poisonous fumes which resulted were allowed to escape into the surrounding countryside.
By the 1860's a more sophisticated form of burning house, the Brunton Calciner, became common.
It had an enclosed revolving hearth, connected to a complex system of flues in which the arsenious oxide was trapped
as a soot, later to be dug out and sold. A tall stack, designed to assist the draught as well as to disperse the
sulphur fumes, marked the end of the flue.
Vertical metal straps on the outside of the Calciner helped the building to withstand the immense heat of the furnace.
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